Please Don’t Activate the Approach

I had someone tell me earlier this week that in order to best understand how to do a certain task, it helps to understand the logic behind how to do that task.  I believe that is true in doing a lot of different tasks in the course of life, but especially true in learning how to use a Garmin GPS unit.  One particular task where understanding the logic, or programming if you will, helps with doing the task is loading and activating an approach.

I’m going to make a blanket statement here, then expound.  Every Garmin GPS unit, whether it’s a Garmin 430 all the way up to a G5000, has a procedures key (PROC).  On the PROC menu that pops up, there is an option for “Activate Approach.”  Don’t use it.

Let’s zoom out and talk about why.  The procedure for selecting an approach is as follows:

  • Press or tap the PROC key
  • Highlight or tap Select Approach, then hit enter (if it’s not a touch screen)
  • Follow the prompts to pick the approach desired and the transition desired
  • At the bottom of the page, there is the option for “Load Approach” and “Activate Approach” (or “Load and Activate Approach”).  Select “Load Approach” to load the approach into the flight plan

This is usually done by the pilot 20-30 minutes from the airport when the ATIS/ASOS/AWOS is received.  The active runway is determined by the pilot, then the proper approach is selected and loaded into the Garmin GPS.  By selecting “Load Approach”, the approach is inserted into the flight plan after the destination airport.  

This throws off the ETA, ETE and distance to destination that the GPS is calculating due to a little “dumbness” in the Garmin GPS unit.  The way the GPS calculates those items is it simply goes line by line in the flight plan, calculating the time and distances between fixes.  Since the approach is after the destination airport in the flight plan, then the GPS is calculating that the plane will fly to the airport first, then turn around and go fly to the Initial Approach Fix (IAF), then commence the rest of the approach.  This is not a big deal, but good to know for the pilot as the ETE will increase once the approach is loaded.  

Foreflight, especially if you have a Garmin Flight Stream, will still be giving accurate times and distances on it’s NAVLOG on the Maps page.  Foreflight puts the approach into the Flight Plan on the Maps page before the destination airport, which makes a little more sense.

Let’s put our fictitious plane and pilot now 10 minutes from the destination airport.  ATC has cleared the pilot direct to the IAF.  The pilot initiates direct to the IAF on the Garmin GPS by highlighting or tapping the IAF on the flight plan and pressing the direct to key.  The Garmin GPS is now giving course guidance direct to the IAF.

Think about what just happened.  The pilot loaded the approach into the flight plan 20-30 minutes from the destination airport.  When ATC cleared the pilot direct to the IAF, the pilot set up the Garmin GPS to navigate direct to the IAF.  What will happen when the plane get’s to the IAF?  The Garmin GPS will sequence over to the next fix in the flight plan, likely the Intermediate Fix (IF), then the next fix, likely the Final Approach Fix (FAF).  There may be an extra fix or two in the flight plan depending on how the approach is configured.  But, the important part is, the Garmin GPS is going to navigate onto and follow the entire approach.  

So, what happened when the pilot initiated Direct to the IAF?  The approach was “activated.”  

Wait, that sounds familiar, doesn’t it?  We talked about “Activate Approach” earlier when we were discussing the pilot’s options on the PROC menu.  Remember, I said, don’t use “Activate Approach”.  Why?  “Activate Approach” simply tells the Garmin GPS to navigate direct to the IAF of the loaded approach.  Most of the time, ATC has already instructed the pilot to navigate direct to the IAF, so there is no need to go to the PROC page and press “Activate Approach.”  The approach is already “activated” and the flight plan will sequence properly.  All “Activate Approach” does is act as a shortcut to navigate directly to the IAF.

Here’s why “Activate Approach” can be dangerous.  In our example above, the pilot has loaded the approach into the flight plan, navigated direct to the IAF, has joined the approach and is about to intercept the glide slope prior to the FAF.  A thought runs through the pilot’s head:  “Oh no, I didn’t activate the approach!”  The pilot then quickly presses PROC and selects “Activate Approach”.  

What happens?  

Exactly.  The plane turns and starts navigating directly to the IAF.  It abandons the approach and does what “Activate Approach” is programmed to do.  This can lead to traffic conflicts, terrain and obstacle conflicts and then overall rattle the pilot.  Typically, this will be at a lower altitude than what the MSA is too.

My advice?  Forget about “Activate Approach” under the PROC menu.  Always use “Direct To” to navigate directly to the IAF.  This is different than “Activate Vectors to Final”, but that’s for another Glass Panel Minute.

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